1. Field of the Invention
This invention relates to the fields of biochemistry and immunology. More specifically, this invention provides a method of in vivo and in vitro stimulation of the production of cytokines for various medicinal, biochemical and physiological effects.
2. Art Background
The lymphocytes or white blood cells in the animal body come in two types, B-cells and T-cells. The B-cells produce antibodies in the form of immunoglobulins that bind onto invading organisms while the T-cells produce the lymphokines or cytokines which are responsible for turning B-cells on or off. It is well known that the growth of normal lymphocytes is dependent not only on contact with an antigenic substance or a mitogen, but also on the presence of certain factors known as lymphokines or cytokines.
The known types of lymphokines include IL-2, B-cell factors, macrophage activation factor (MAF), Interleukin-3 (IL-3), Colony Stimulating Factor (CSF), Tumor Necrosis Factor (TNF), and other factors produced by monocytes such as Interleukin-1 (IL-1) and Gamma Interferon. All of these factors are secreted by white blood cells and are collectively known as cytokines.
Monocytes can be stimulated by various agents, such as LPS (lipopolysaccharides), to produce certain cytokines including TNF, IL-1 and IL-6. LPS contain a polysaccharide and a lipid A part. Polysaccharides such as .beta.1-3 glucans and blocks of .beta.1-4 D-mannuronic acid have been reported to stimulate monocytes to produce cytokines. Seljelid R., Figenschau Y., Bogwald J., Rasmussen L. T. and R. Austgulen. 1989. Evidence that Tumour Necrosis Induced by Aminated .beta.1-3D Polyglucose is Mediated by a Concerted Action of Local and Systemic Cytokines. Scand. J. Immunol., 30:687; Otterlei M., Ostgaard K., Skj.ang.k-Br k G., Smidsrod O. and T. Espevik. 1991. Induction of cytokine production from human monocytes stimulated with alginate, J. of Immunotherapy, in press.
The present invention relates generally to cytokines, and particularly to the stimulation of biologically active mammalian IL-1, IL-6 and TNF. Interleukin-1 is the designation given to a family of polypeptides, released by macrophages and certain other cell types in response to immunogenic and traumatic stimulation, which have a primary role in initiating host response to injury and infection. These cytokines have been associated with a complex spectrum of biological activities. Specifically, IL-1 is a primary immunostimulatory signal capable of inducing thymocyte proliferation via induction of Interleukin-2 release, and of stimulating proliferation and maturation of B lymphocytes. In addition, IL-1 has been linked with prostaglandin production, induction of fever and promotion of wound healing.
In recent years, immunotherapy has become more and more important in the field of applied medicine. For instance opportunistic infections are frequently observed in newborn children with functional immunodeficiency, cancer patients, patients transplanted with bone marrows, patients receiving chemotherapeutic agents or steroids, and aged patients. Antibiotics so far used in these field against infections do not exert significant effect in immuno-deficient or immuno-depressed patients. The situation is almost the same in viral infections, and effective chemotherapeutic agents against viral infections has not been so far provided for clinical uses. Interferon has been reported to have some effects against viral infections; however, the nature of the interferons is still unclear and there is uncertainty as to the action modes. Therefore, interferon has not yet been confirmed for its effectiveness. The uncertainty of the effectiveness of interferon is also due to the fact that human interferon does not function in animal model. The presents of species-specificity may be one of the major difficulty for the development of interferon as therapeutic agents.
In the field of cancer, the situation of the development of effective therapeutic drugs is analogous to those in infectious diseases and viral diseases. In cancer patients, the prominent depression of immunological function of the host has been widely confirmed, and therefore immunotherapy and immunochemotherapy (adjuvant therapy) have drawn much attention as new definite methods to treat cancer patients. Immunotherapy has been said not only to restore or potentiate the specific immune responses against cancer, but also to improve the general function of host including immunological functions. So far several immunomodulators have been applied in clinics, however almost all of these share the nature of chemotherapeutic agents in such a manner that they also exert direct cytocidal effects against neoplastic cells.
Recently, an immunotherapeutic agent identified as an antitumor polysaccharide was confirmed for its clinical effectiveness in phase III clinical test. This agent exerts its antitumor effects by augmenting the reactivity of pre-effector cells to several kinds of cytokines.
Generally speaking, several antigens or immunogens containing the antigens are also used as vaccines in active immunotherapy. However the active immunotherapy does not function when the immunological functions of the host are depressed or defective such as in cancer, infections and viral diseases. In order to augment humoral immune responses, the administration of gamma-globulin together with the vaccines might be useful. However, when cell-mediated immunity play key roles, the methods is not practical. In such cases, cytokines might be useful when used in combination with vaccines such as tumor specific antigens instead of gamma-globulin in the augmentation of humoral immune responses.
Additionally, research has demonstrated that IL-1, TNF, and other leukocyte derived cytokines are important, and even critical, mediators in a wide variety of inflammatory states and diseases. The immunostimulating activities of cytokines may be important for treatment of neoplastic as well as for infectious diseases, and may have potential anti-tumor, anti-bacteriological anti-fungal and antiviral effects. Additionally, therapeutic compositions comprising biologically active quantities of certain cytokines and derivatives could be employed to potentiate antibody production in response to vaccine antigens. Also, in view of potential therapeutic utility as vaccine adjuvants and components of wound-healing compositions, there is interest in employing cytokines in veterinary medicine.